The present invention relates to the field of plumbing and more particularly to gas shut off valves.
Natural gas, because it is a clean and inexpensive energy source, is used to power many domestic and industrial appliances, such as stoves, ovens, and water heaters. Natural gas is supplied to many residences and businesses in this country via networks of underground pipes. These networks are owned, operated and maintained by various gas utility companies. In the Los Angeles area, for example, the local gas utility is the Southern California Gas Company.
In order to monitor the use of natural gas by its customers, each gas utility typically installs a gas meter at the service entrance of each residence or business that it services. Additionally, in order to facilitate hook-up, provide for emergency shut off, and control access to only those customers who are authorized, the gas utility installs a gas shut off valve ahead of the gas meter. The shut off valve is generally connected to the meter by a short length of pipe known as a nipple.
Gas shut off valves have existed for many years. Some early designs were patented but these patents have now expired. A typical gas shut off valve used by the gas utilities at their service entrances is model 10685B, manufactured by A. Y. McDonald Manufacturing Company of Dubuque, Iowa. Because they must be fairly easy to operate in an emergency, gas shut off valves can generally be opened and closed with a commonly available wrench. A handle or tab, exterior to the valve body, is provided for this purpose. As part of their emergency preparations, many responsible home and business owners are aware of how to open and close the gas shut off valve. In fact, in the interests of safety, the gas utilities provide this knowledge to their customers.
Unfortunately, the gas utilities must use this same gas shut off valve to cut off service in case customers become delinquent in paying their bills. Using a wrench, many unscrupulous customers, simply turn the gas back on as soon as the gas company employee has turned it off.
Faced with this problem, the gas utilities have sought ways of locking standard gas shut off valves. Some involved use of boxes locked in place over the valve. However, these were easy to defeat or destroy. The most successful device to-date has been a special plug lock that installs in the female threads of the gas valve. This lock replaces the nipple between the valve and the gas meter.
This special lock is manufactured by Inner-Tite Corporation of Springfield, N.J. Their model numbers are G-1320 through G-1370, G-4320 through G-4370, G-1320A through G-1370A, G-4320A through G-4370A, G-1320C through G-1370C, and G-4320C through G-4370C. The lock consists of four components, a plug which threads into the female threads of the gas valve, has wrenching flats, and a special bore at its outer end; an outer body which slips over the plug; and a barrel lock, which secures the body to the bore in the plug. The barrel lock can only be inserted and removed from the plug with a special key. Once the outer body is installed, the wrenching flats cannot be reached and the entire assembly cannot be removed because the outer body turns freely on the plug. The barrel lock and the key are covered under U.S. Pat. Nos. 3,867,822 and 4,289,000.
Availability of the key is limited. Furthermore, customers are reluctant to tamper with the collar because of the fear of damaging the gas supply line. The main disadvantage of using the collar is that to use it the gas service must be disassembled. This is an expensive, time consuming and sometimes dangerous operation.
Use of the Inner-Tite plug locks listed above has been very effective in solving the gas companies' problems. However, installation of the lock necessitates disassembly of the service entrance. Development of a gas valve which had all the positive features of the Inner-Tite lock yet would be lockable without disassembly of the gas service would represent a great improvement in the field of gas shut off valves and satisfy a long felt need of the gas utilities and their employees.